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Pacific walrus vision: the science and the numbers

Odobenus rosmarus · order Carnivora · Mammals: all the numbers

Its sharpest vision resolves 3.8 cycles per degree, against 63.75 for people in this dataset.[8] Its activity pattern is cathemeral.[15][2][16][17][18][19]

See it on your photoBack to How does the Pacific walrus see?
  • 3.8cycles per degree (sharpness)Measured

The Pacific walrus (Odobenus rosmarus) is a mammal in the order Carnivora. Its eyes belong to the vision type Marine mammal cone monochromat: a single cone type, so no hue at all, in a rod-dominated eye. Measured in this species: sharpness, foveas and night vision. Measured core: measured values on at least 3 of the 6 dials.

This is a simulation built from published eye measurements, not what the animal experiences.

Method: How we know what animals see (the See Like Animals vision engine) · Sources · Last updated . Every value below carries its evidence level and sources; nothing is typed by hand.

What the Pacific walrus sees: colour receptors

Pacific walrus colour receptor peaks, 300 to 700 nmPacific walrus: 1 receptor peak at 362 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Pacific walrus: 362 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • Its sharpest vision resolves 3.8 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • Activity pattern: cathemeral.

The six dials

Evidence levels: how the tiers work. "Measured" means a value measured in this species; "Estimated" values come from a close relative or an eye-size formula. The last column gives the values for people from the same catalogue.

Vision values for the Pacific walrus (Odobenus rosmarus), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
1 receptor class: 362 nm (UVS)
ESTIMATE: receptor classes from opsin-gene presence in this species; lambda max per class from the measured class template of the nearest taxon (never from the gene itself)
Group default[1][2][3][4][5]Colour receptors: 3 receptor classes: 421.5 nm (VS/SWS (violet)), 532 nm (MWS (green)), 558.4 nm (LWS (long)) Measured (not re-verified)[3][6][4][7]
Ultraviolet
yes: at least one receptor peaks in the ultraviolet		Group default
SharpnessAcuity
3.8 cycles per degree
median of 1 anatomical-ganglion rows (method priority rule)
Measured[8]Acuity: 63.75 cycles per degree Measured[9][8]
Field of viewBinocular overlap
88.5°
median of 4 relatives in order Carnivora: Canis lupus, Felis catus, Mustela putorius, Mustela nivalis
Group default[10][11]Binocular overlap: 122.5° Measured[10][11]
Total field of view: 200° Measured (not re-verified)[12]
Blind area behind the head: 160° Derived[12]
Eye placement: frontal Derived[10][11]
Total field of view
250°
median species-v1 total field of order Carnivora: Canis familiaris
Group default[13]
Sharp zones (foveas)Number of foveas
0
fovea_present / area_centralis_type (retinal topography; count 1 = fovea present, 0 = none)
Measured[14]Number of foveas: 1 Measured[14]
Fovea type: fovea Measured[14]
Fovea type
area centralis		Measured[14]
Night visionActivity pattern
cathemeral
mode of 4 rows (of 6 rows): aquatic; arrhythmic/cathemeral; cathemeral; diurnal; mixed (nocturnal/crepuscular, cathemeral, crepuscular or diurnal/crepuscular)
Measured (not re-verified)[15][2][16][17][18][19]Activity pattern: diurnal Measured (not re-verified)[15][2][16][3][17][18][20][19]
Pupil shape: vertical Group default[21][22]
Reflective layer (tapetum): no Measured[23]
Rods vs cones: cone-dominated Derived[15][2][16][3][17][18][20][19]
Rods vs cones
mixed
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[15][2][16][17][18][19]
Motion (flicker fusion)Flicker fusion frequency
76.25 Hz
median of 4 relatives in order Carnivora: Felis catus, Canis lupus, Pagophilus groenlandicus, Canis familiaris
Group default[24][25][26][27]Flicker fusion frequency: 60 Hz Measured[25][26]

All mammals side by side: Mammals: every measurement. Method: how we know what animals see.

Sources

  1. Cone topography and spectral sensitivity in… 2005
  2. Borges et al. 2018
  3. Longcore 2023
  4. Müller et al. 2009
  5. VPOD in-vivo (MSP / single-cell) lambda… 2025
  6. Kirwan
  7. Thermal Activation and Photoactivation of Visual… 2004
  8. Veilleux et al. 2014
  9. Kirk et al. 2004
  10. Heesy 2004
  11. Heffner et al. 1992
  12. Campbell & Green 1965
  13. Miller & Murphy 1995
  14. Kopania et al. 2025
  15. Anderson et al. 2017
  16. Wilman et al. 2014
  17. Maor et al. 2017
  18. Jones et al. 2009
  19. Moura et al. 2024
  20. Schmitz et al. 2011
  21. Banks et al. 2015
  22. Cervino et al. 2021
  23. Guareschi et al. 2025
  24. Haarlem et al. 2026
  25. Healy et al. 2013
  26. Inger et al. 2014
  27. Lafitte et al. 2022

Every value cites its sources (all sources). Values were extracted from these works and converted (units, medians, derived values); changes are ours, and the listed sources do not endorse this site. Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this? Method: how we know.